Heat transfer medium



Patented Oct. 31, 1933 UNITED STATES PATENT OFFICE HEAT TRANSFE R MEDIUM No Drawing.

Application June 21, 1932 Serial No. 618,564

9 Claims.

which is secured by vaporization of gaseous compounds or mixtures which have been condensed to their liquid state.

Numerous gases have been used as refrigerants for producing moderately low temperatures, such as are required in the ordinary household or small commercial refrigeration units. Most of these rerfigerants are objectionable in that they present certain hazards owing to their toxicity, instability or inflammability.

When very low temperatures are desired certain refrigerants present other difliculties, for instance, the solidification of the refrigerant at temperatures higher than desired. This results in the formation of solid masses at points in the refrigeration system which may interfere with the operation thereof. Thus, under certain conditions carbon dioxide solidifies if allowed to cool to or below certain desirable temperatures. This invention has as an object the provision of a new and improved refrigerant and a process of refrigeration employing that refrigerant. Another object is to provide a refrigerant which is non-inflammable, practically non-toxic, and

stable under operating and atmospheric condi-.

tions. A further object is to provide a refrigerant of low boiling point, low affinity for water, and a solidification point low enough to prevent blockage of the refrigeration system by freezing of the refrigerant at any stage in the heat transfer cycle. Other objects will appear hereinafter.

These objects are accomplished by evaporating and condensing a compound of sulfur, oxygen, and fluorine such as sulfuryl fluoride (SO2F2) in a heat transfer system. This compound isnOninflammable and very stable, being practically inert under both operating and atmospheric conditions. Also, as far as it has been ascertained, its toxicity is very low. Sulphuryl fluoride boils at a temperature of 52 C. at atmospheric pressure, and solidifies at the much lower temperature of 120 C. It further possesses the property of having practically no affinity for water under the usual operating temperature for any refrigerating or heat transfer system in which it might be used.

Sulphuryl fluoride, may be advantageously used in well-known types of refrigeration systems such as, for example, the so-called flooded and dry systems. By a flooded system is meant one in which a relatively larger amount of the liquid refrigerant is retained in the evaporator and evaporation takes place from the surface of the liquid as a result of the reduction of surface tension of the liquid. The dry system is that type in which the evaporation of the liquid takes I place during its release through an expansion or regulating valve into the cooling chamber or coils. The liberated gas may be condensed by compression and cooling or in any other suitable manner. If desired, the system may include a suitable absorbent for the gas liberated. Sulphuryl fluoride is also adapted for use as a cooling agent by spraying the liquid refrigerant over the article to be cooled and permitting evaporation therefrom, or by immersing the body to be cooled in the liquid refrigerant, and by similar processes.

Sulphuryl fluoride possesses the necessary physical characteristics of a good refrigerant since, as shown above, it boils at a low temperature and solidifies at a considerably lower temperature. A refrigerant of such a low freezing point and such a wide difference between freezing and boiling points would not solidify within a refrigeration system under any usual range of operating temperatures, and thereby eliminates one of the objections to the more common refrigerants now employed. Since it has low affinity for water it is easily maintained in dry form.

As an illustration of another compound falling within the broader aspects of the invention thionyl fluoride (SOF2) may be mentioned. It has a somewhat higher boiling point (31 C.) than sulfuryl fluoride but is less desirable from the standpoint of stability.

As many apparent and widely different embodiments of this invention may be made without departing from the spirit thereof, it is to be understood that we do not limit ourselves to the foregoing description except as indicated in the following claims.

We claim:

1. The process of transferring heat, which comprises condensing a gaseous substance containing a compound of sulphur, oxygen and fluorine, and evaporating the condensate.

2. The process of transferring heat, which comprises condensing a gaseous substance containing a compound having the following general formula:

SOzrF:

wherein m is an integer not greater than 2, and evaporating the condensate.

3. The process of transferring heat, which comprises condensing a gas containing sulphuryl fluoride, and evaporating the condensate.

4. The process of transferring heat, which comprises condensing a gas containing sulphuryl fluoride, and evaporating the condensate or a portion thereof in the vicinity of a body to be cooled.

5. The method of refrigeration which comprises liberating, subject to control at a relatively low pressure, sulphuryl fluoride artificially maintained as a liquid until liberated.

6. The method of refrigeration which comprises liberating at a relatively low pressure liquid sulphuryl fluoride in the vicinity of a ho to be cooled.

7. The method of refrigeration, which consists HERBERT WILKENS DAUDT. JOHN ELTON COLE. 

